Thursday marks the 100-year anniversary of the United States' official entry into World War I, just four days after Woodrow Wilson asked Congress for a declaration of war on Germany in 1917.

The year was full of highs and lows for the US - an Illinois tornado killed more than 100 people, the first Pulitzer Prize was awarded and several hundred Oklahoma farmers rallied against the draft during the Green Corn Rebellion. Nine Milwaukee police officers were killed by a bomb in November, marking the most fatal single event in US police history until the September 11 attacks. The New York Guard was also founded in August.